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1.
J Manag Care Spec Pharm ; 30(7): 672-683, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38950155

ABSTRACT

BACKGROUND: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are rare oncogenic drivers prevalent in 0.3% of solid tumors. They are most common in salivary gland cancer (2.6%), thyroid cancer (1.6%), and soft-tissue sarcoma (1.5%). Currently, there are 2 US Food and Drug Administration-approved targeted therapies for NTRK gene fusions: larotrectinib, approved in 2018, and entrectinib, approved in 2019. To date, the real-world uptake of tyrosine receptor kinase inhibitor (TRKi) use for NTRK-positive solid tumors in academic cancer centers remains largely unknown. OBJECTIVE: To describe the demographics, clinical and genomic characteristics, and testing and treatment patterns of patients with NTRK-positive solid tumors treated at US academic cancer centers. METHODS: This was a retrospective chart review study conducted in academic cancer centers in the United States. All patients diagnosed with an NTRK fusion-positive (NTRK1, NTRK2, NTRK3) solid tumor (any stage) and who received cancer treatment at participating sites between January 1, 2012, and July 1, 2023, were included in this study. Patient demographics, clinical characteristics, genomic characteristics, NTRK testing data, and treatment patterns were collected from electronic medical records and analyzed using descriptive statistics as appropriate. RESULTS: In total, 6 centers contributed data for 55 patients with NTRK-positive tumors. The mean age was 49.3 (SD = 20.5) years, 51% patients were female, and the majority were White (78%). The median duration of time from cancer diagnosis to NTRK testing was 85 days (IQR = 44-978). At the time of NTRK testing, 64% of patients had stage IV disease, compared with 33% at cancer diagnosis. Prevalent cancer types in the overall cohort included head and neck (15%), thyroid (15%), brain (13%), lung (13%), and colorectal (11%). NTRK1 fusions were most common (45%), followed by NTRK3 (40%) and NTRK2 (15%). Across all lines of therapy, 51% of patients (n = 28) received a TRKi. Among TRKi-treated patients, 71% had stage IV disease at TRKi initiation. The median time from positive NTRK test to initiation of TRKi was 48 days (IQR = 9-207). TRKis were commonly given as first-line (30%) or second-line (48%) therapies. Median duration of therapy was 610 (IQR = 182-764) days for TRKi use and 207.5 (IQR = 42-539) days for all other first-line therapies. CONCLUSIONS: This study reports on contemporary real-world NTRK testing patterns and use of TRKis in solid tumors, including time between NTRK testing and initiation of TRKi therapy and duration of TRKi therapy.


Subject(s)
Neoplasms , Protein Kinase Inhibitors , Receptor, trkA , Receptor, trkB , Receptor, trkC , Humans , Female , Male , Retrospective Studies , Middle Aged , United States , Neoplasms/genetics , Neoplasms/drug therapy , Receptor, trkC/genetics , Aged , Receptor, trkA/genetics , Adult , Protein Kinase Inhibitors/therapeutic use , Receptor, trkB/genetics , Academic Medical Centers , Membrane Glycoproteins/genetics , Oncogene Proteins, Fusion/genetics , Cohort Studies , Pyrimidines/therapeutic use , Pyrazoles/therapeutic use , Benzamides/therapeutic use , Young Adult , Indazoles/therapeutic use
2.
Popul Health Manag ; 26(S1): S21-S22, 2023 08.
Article in English | MEDLINE | ID: mdl-37603808
3.
Am J Manag Care ; 28(6 Suppl): S112-S119, 2022 08.
Article in English | MEDLINE | ID: mdl-35997775

ABSTRACT

OBJECTIVES: Clinical practice guidelines recommend at least annual testing of estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (uACR) for patients with chronic kidney disease (CKD) and type 2 diabetes (T2D). This study assessed the adequacy of eGFR and uACR testing in this patient population across the United States. STUDY DESIGN: Observational real-world study. METHODS: Adults with CKD and T2D were identified from the Optum Clinformatics database (2015-2019). The eGFR and uACR tests were assessed nationally and by state. The proportions of tested patients and patients receiving adequate monitoring per clinical practice guidelines were analyzed during the 1-year period after T2D and CKD diagnosis, along with all-cause health care costs. RESULTS: Among 101,057 adults with CKD and T2D, 94.1% had at least 1 eGFR test and 38.7% had at least 1 uACR test over 1 year. Only 20.3% of patients had adequate uACR monitoring; this was much lower than observed for adequate eGFR monitoring (86.6%). The eGFR testing rates were high across states (range, 79.5% [Colorado] to 97.3% [Alabama]); conversely, uACR testing rates were uniformly lower and showed wider variation (range, 14.0% [Maine] to 58.9% [Hawaii]). Mean annual all-cause health care costs were $28,636 and increased with CKD GFR stage. Lower uACR testing rates were associated with higher health care costs at the state level (Pearson r = -0.55; P < .01). CONCLUSIONS: In the United States, uACR testing is underutilized, with large geographical variations in testing rates noted between states. Lower uACR testing rates were associated with higher health care costs. The lack of sufficient uACR testing raises concerns about CKD management in patients with T2D.


Subject(s)
Diabetes Mellitus, Type 2 , Renal Insufficiency, Chronic , Adult , Albuminuria/diagnosis , Albuminuria/epidemiology , Albuminuria/etiology , Diabetes Mellitus, Type 2/complications , Health Care Costs , Humans , Kidney , Renal Insufficiency, Chronic/complications , Renal Insufficiency, Chronic/diagnosis , Renal Insufficiency, Chronic/epidemiology , United States
4.
Cells ; 10(9)2021 09 19.
Article in English | MEDLINE | ID: mdl-34572130

ABSTRACT

BACKGROUND: Whole transgenic or non-transgenic organism model systems allow the screening of pharmacological compounds for protective actions in Alzheimer's disease (AD). AIM: In this study, a plant parasitic nematode, Globodera pallida, which assimilates intact peptides from the external environment, was investigated as a new potential non-transgenic model system of AD. Methods: Fresh second-stage juveniles of G. pallida were used to measure their chemosensory, perform immunocytochemistry on their neurological structures, evaluate their survival rate, measure reactive oxygen species, and determine total oxidized glutathione to reduced glutathione ratio (GSSG/GSH) levels, before and after treatment with 100 µM of various amyloid beta (Aß) peptides (1-40, 1-42, 17-42, 17-40, 1-28, or 1-16). Wild-type N2 C. elegans (strain N2) was cultured on Nematode Growth Medium and directly used, as control, for chemosensory assays. RESULTS: We demonstrated that: (i) G. pallida (unlike Caenorhabditis elegans) assimilates amyloid-ß (Aß) peptides which co-localise with its neurological structures; (ii) pre-treatment with various Aß isoforms (1-40, 1-42, 17-42, 17-40, 1-28, or 1-16) impairs G. pallida's chemotaxis to differing extents; (iii) Aß peptides reduced survival, increased the production of ROS, and increased GSSG/GSH levels in this model; (iv) this unique model can distinguish differences between different treatment concentrations, durations, and modalities, displaying good sensitivity; (v) clinically approved neuroprotective agents were effective in protecting G. pallida from Aß (1-42) exposure. Taken together, the data indicate that G. pallida is an interesting in vivo model with strong potential for discovery of novel bioactive compounds with anti-AD activity.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Peptides/toxicity , Animals, Genetically Modified/physiology , Neuroprotective Agents/pharmacology , Oxidative Stress/drug effects , Reactive Oxygen Species/metabolism , Tylenchoidea/physiology , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Animals , Caenorhabditis elegans/drug effects , Caenorhabditis elegans/physiology , Chemotaxis , Tylenchoidea/drug effects
5.
Int J Parasitol ; 51(9): 693-698, 2021 08.
Article in English | MEDLINE | ID: mdl-33848496

ABSTRACT

We conducted a transcriptomic and small RNA analysis of infective juveniles (IJs) from three behaviourally distinct Steinernema species. Substantial variation was found in the expression of shared gene orthologues, revealing gene expression signatures that correlate with behavioural states. Ninety-seven percent of predicted microRNAs are novel to each species. Surprisingly, our data provide evidence of a new family of non-coding transcripts that overlap with neuropeptide gene loci, which are predicted to influence microRNA regulation of neuropeptide genes. These data suggest that differences in neuropeptide gene expression, isoform variation, and small RNA interactions could contribute to behavioural differences within the Steinernema genus.


Subject(s)
Host-Seeking Behavior , MicroRNAs , Neuropeptides , Rhabditida , Animals , MicroRNAs/genetics , Neuropeptides/genetics , Transcriptome
6.
JAMA Health Forum ; 2(12): e214205, 2021 12.
Article in English | MEDLINE | ID: mdl-35977296

ABSTRACT

This cross-sectional study evaluates the stipulations of coverage under commercial, health insurance exchange, Veterans Affairs, Medicare, Medicaid, or other insurance for canagliflozin, dapagliflozin, empagliflozin, and ertugliflozin.


Subject(s)
Diabetes Mellitus, Type 2 , Drug Costs , Insurance, Health , Sodium-Glucose Transporter 2 Inhibitors , Humans , Blood Glucose , Costs and Cost Analysis , Cross-Sectional Studies , Diabetes Mellitus, Type 2/drug therapy , Hypoglycemic Agents/economics , Medicare , Sodium-Glucose Transporter 2 Inhibitors/economics , United States
8.
BMC Genomics ; 20(1): 884, 2019 Nov 21.
Article in English | MEDLINE | ID: mdl-31752671

ABSTRACT

BACKGROUND: Steinernema carpocapsae is an entomopathogenic nematode that employs nictation and jumping behaviours to find potential insect hosts. Here we aimed to investigate the transcriptional basis of variant host-finding behaviours in the infective juvenile (IJ) stage of three S. carpocapsae strains (ALL, Breton and UK1), with a focus on neuronal genes known to influence behaviour in other nematode species. Identifying gene expression changes that correlate with variant host-finding behaviours will further our understanding of nematode biology. RESULTS: RNA-seq analysis revealed that whilst up to 28% of the S. carpocapsae transcriptome was differentially expressed (P < 0.0001) between strains, remarkably few of the most highly differentially expressed genes (> 2 log2 fold change, P < 0.0001) were from neuronal gene families. S. carpocapsae Breton displays increased chemotaxis toward the laboratory host Galleria mellonella, relative to the other strains. This correlates with the up-regulation of four srsx chemosensory GPCR genes, and a sodium transporter gene, asic-2, relative to both ALL and UK1 strains. The UK1 strain exhibits a decreased nictation phenotype relative to ALL and Breton strains, which correlates with co-ordinate up-regulation of neuropeptide like protein 36 (nlp-36), and down-regulation of an srt family GPCR gene, and a distinct asic-2-like sodium channel paralogue. To further investigate the link between transcriptional regulation and behavioural variation, we sequenced microRNAs across IJs of each strain. We have identified 283 high confidence microRNA genes, yielding 321 predicted mature microRNAs in S. carpocapsae, and find that up to 36% of microRNAs are differentially expressed (P < 0.0001) between strains. Many of the most highly differentially expressed microRNAs (> 2 log2 fold, P < 0.0001) are predicted to regulate a variety of neuronal genes that may contribute to variant host-finding behaviours. We have also found evidence for differential gene isoform usage between strains, which alters predicted microRNA interactions, and could contribute to the diversification of behaviour. CONCLUSIONS: These data provide insight to the transcriptional basis of behavioural variation in S. carpocapsae, supporting efforts to understand the molecular basis of complex behaviours in nematodes.


Subject(s)
Genes, Helminth , Host-Parasite Interactions/genetics , Rhabditida/genetics , Animals , Behavior, Animal , Ion Channels/genetics , MicroRNAs/genetics , Neuropeptides/genetics , Receptors, G-Protein-Coupled/genetics , Rhabditida/growth & development , Transcriptome
9.
Int J Parasitol ; 49(11): 837-841, 2019 10.
Article in English | MEDLINE | ID: mdl-31525369

ABSTRACT

Meloidogyne incognita is an economically important plant parasitic nematode. Here we demonstrate substantial variation in the invasiveness of four M. incognita populations relative to tomato. Infective (J2) stage transcriptomes reveal significant variation in the expression of protein-coding and non-coding RNAs between populations. We identify 33 gene expression markers that correlate with invasiveness, and which map to genes with predicted roles in host finding and invasion, including neuropeptides, ion channels, G Protein-Coupled Receptors, cell wall-degrading enzymes and microRNAs. These data demonstrate a surprising diversity in microRNA complements between populations, and identify gene expression markers for invasiveness of M. incognita, to our knowledge for the first time.


Subject(s)
Plant Diseases/parasitology , Solanum lycopersicum/parasitology , Transcriptome , Tylenchoidea/growth & development , Tylenchoidea/pathogenicity , Animals , Gene Expression Profiling , Helminth Proteins/genetics , MicroRNAs/analysis , Tylenchoidea/genetics , Virulence , Virulence Factors/genetics
10.
PLoS Pathog ; 13(3): e1006185, 2017 03.
Article in English | MEDLINE | ID: mdl-28253355

ABSTRACT

Entomopathogenic nematodes (EPNs) employ a sophisticated chemosensory apparatus to detect potential hosts. Understanding the molecular basis of relevant host-finding behaviours could facilitate improved EPN biocontrol approaches, and could lend insight to similar behaviours in economically important mammalian parasites. FMRFamide-like peptides are enriched and conserved across the Phylum Nematoda, and have been linked with motor and sensory function, including dispersal and aggregating behaviours in the free living nematode Caenorhabditis elegans. The RNA interference (RNAi) pathway of Steinernema carpocapsae was characterised in silico, and employed to knockdown the expression of the FMRFamide-like peptide 21 (GLGPRPLRFamide) gene (flp-21) in S. carpocapsae infective juveniles; a first instance of RNAi in this genus, and a first in an infective juvenile of any EPN species. Our data show that 5 mg/ml dsRNA and 50 mM serotonin triggers statistically significant flp-21 knockdown (-84%***) over a 48 h timecourse, which inhibits host-finding (chemosensory), dispersal, hyperactive nictation and jumping behaviours. However, whilst 1 mg/ml dsRNA and 50 mM serotonin also triggers statistically significant flp-21 knockdown (-51%**) over a 48 h timecourse, it does not trigger the null sensory phenotypes; statistically significant target knockdown can still lead to false negative results, necessitating appropriate experimental design. SPME GC-MS volatile profiles of two EPN hosts, Galleria mellonella and Tenebrio molitor reveal an array of shared and unique compounds; these differences had no impact on null flp-21 RNAi phenotypes for the behaviours assayed. Localisation of flp-21 / FLP-21 to paired anterior neurons by whole mount in situ hybridisation and immunocytochemistry corroborates the RNAi data, further suggesting a role in sensory modulation. These data can underpin efforts to study these behaviours in other economically important parasites, and could facilitate molecular approaches to EPN strain improvement for biocontrol.


Subject(s)
Gene Knockdown Techniques/methods , Host-Parasite Interactions/physiology , Nematoda/physiology , Neuropeptides/metabolism , Animals , Chromatography, Gas , Genes, Helminth , Immunohistochemistry , In Situ Hybridization , Mass Spectrometry , Real-Time Polymerase Chain Reaction
11.
PLoS Pathog ; 13(2): e1006237, 2017 02.
Article in English | MEDLINE | ID: mdl-28241060

ABSTRACT

Plant parasitic nematodes (PPNs) seriously threaten global food security. Conventionally an integrated approach to PPN management has relied heavily on carbamate, organophosphate and fumigant nematicides which are now being withdrawn over environmental health and safety concerns. This progressive withdrawal has left a significant shortcoming in our ability to manage these economically important parasites, and highlights the need for novel and robust control methods. Nematodes can assimilate exogenous peptides through retrograde transport along the chemosensory amphid neurons. Peptides can accumulate within cells of the central nerve ring and can elicit physiological effects when released to interact with receptors on adjoining cells. We have profiled bioactive neuropeptides from the neuropeptide-like protein (NLP) family of PPNs as novel nematicides, and have identified numerous discrete NLPs that negatively impact chemosensation, host invasion and stylet thrusting of the root knot nematode Meloidogyne incognita and the potato cyst nematode Globodera pallida. Transgenic secretion of these peptides from the rhizobacterium, Bacillus subtilis, and the terrestrial microalgae Chlamydomonas reinhardtii reduce tomato infection levels by up to 90% when compared with controls. These data pave the way for the exploitation of nematode neuropeptides as a novel class of plant protective nematicide, using novel non-food transgenic delivery systems which could be deployed on farmer-preferred cultivars.


Subject(s)
Antinematodal Agents/pharmacology , Neuropeptides/pharmacology , Pest Control, Biological/methods , Plant Diseases/parasitology , Secernentea Infections , Animals , Organisms, Genetically Modified , Soil Microbiology , Tylenchoidea
12.
Int J Parasitol ; 46(8): 473-7, 2016 07.
Article in English | MEDLINE | ID: mdl-27033013

ABSTRACT

Plant parasitic nematodes (PPN) locate host plants by following concentration gradients of root exudate chemicals in the soil. We present a simple method for RNA interference (RNAi)-induced knockdown of genes in tomato seedling roots, facilitating the study of root exudate composition, and PPN responses. Knockdown of sugar transporter genes, STP1 and STP2, in tomato seedlings triggered corresponding reductions of glucose and fructose, but not xylose, in collected root exudate. This corresponded directly with reduced infectivity and stylet thrusting of the promiscuous PPN Meloidogyne incognita, however we observed no impact on the infectivity or stylet thrusting of the selective Solanaceae PPN Globodera pallida. This approach can underpin future efforts to understand the early stages of plant-pathogen interactions in tomato and potentially other crop plants.


Subject(s)
Host-Seeking Behavior/physiology , Monosaccharides/metabolism , Plant Exudates/physiology , RNA Interference/physiology , Solanum lycopersicum/parasitology , Tylenchoidea/physiology , Animals , Chemotaxis , Fructose/metabolism , Gene Knockdown Techniques , Glucose/metabolism , Solanum lycopersicum/metabolism , Monosaccharides/genetics , Plant Exudates/genetics , Plant Exudates/metabolism , Plant Roots/metabolism , Plant Roots/parasitology , RNA, Double-Stranded/physiology , Seedlings/metabolism , Seedlings/parasitology , Xylose/metabolism
13.
Ecol Evol ; 5(19): 4365-75, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26664685

ABSTRACT

How much should an individual invest in immunity as it grows older? Immunity is costly and its value is likely to change across an organism's lifespan. A limited number of studies have focused on how personal immune investment changes with age in insects, but we do not know how social immunity, immune responses that protect kin, changes across lifespan, or how resources are divided between these two arms of the immune response. In this study, both personal and social immune functions are considered in the burying beetle, Nicrophorus vespilloides. We show that personal immune function declines (phenoloxidase levels) or is maintained (defensin expression) across lifespan in nonbreeding beetles but is maintained (phenoloxidase levels) or even upregulated (defensin expression) in breeding individuals. In contrast, social immunity increases in breeding burying beetles up to middle age, before decreasing in old age. Social immunity is not affected by a wounding challenge across lifespan, whereas personal immunity, through PO, is upregulated following wounding to a similar extent across lifespan. Personal immune function may be prioritized in younger individuals in order to ensure survival until reproductive maturity. If not breeding, this may then drop off in later life as state declines. As burying beetles are ephemeral breeders, breeding opportunities in later life may be rare. When allowed to breed, beetles may therefore invest heavily in "staying alive" in order to complete what could potentially be their final reproductive opportunity. As parental care is important for the survival and growth of offspring in this genus, staying alive to provide care behaviors will clearly have fitness payoffs. This study shows that all immune traits do not senesce at the same rate. In fact, the patterns observed depend upon the immune traits measured and the breeding status of the individual.

14.
Int J Parasitol ; 45(11): 673-8, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26149642

ABSTRACT

The sustainable control of animal parasitic nematodes requires the development of efficient functional genomics platforms to facilitate target validation and enhance anthelmintic discovery. Unfortunately, the utility of RNA interference (RNAi) for the validation of novel drug targets in nematode parasites remains problematic. Ascaris suum is an important veterinary parasite and a zoonotic pathogen. Here we show that adult A. suum is RNAi competent, and highlight the induction, spread and consistency of RNAi across multiple tissue types. This platform provides a new opportunity to undertake whole organism-, tissue- and cell-level gene function studies to enhance target validation processes for nematode parasites of veterinary/medical significance.


Subject(s)
Ascaris suum/genetics , Gene Expression Regulation , RNA Interference , Animals
15.
PLoS One ; 9(2): e89521, 2014.
Article in English | MEDLINE | ID: mdl-24586845

ABSTRACT

Red squirrels (Sciurus vulgaris) declined in Great Britain and Ireland during the last century, due to habitat loss and the introduction of grey squirrels (Sciurus carolinensis), which competitively exclude the red squirrel and act as a reservoir for squirrelpox virus (SQPV). The disease is generally fatal to red squirrels and their ecological replacement by grey squirrels is up to 25 times faster where the virus is present. We aimed to determine: (1) the seropositivity and prevalence of SQPV DNA in the invasive and native species at a regional scale; (2) possible SQPV transmission routes; and, (3) virus degradation rates under differing environmental conditions. Grey (n = 208) and red (n = 40) squirrel blood and tissues were sampled. Enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qPCR) techniques established seropositivity and viral DNA presence, respectively. Overall 8% of squirrels sampled (both species combined) had evidence of SQPV DNA in their tissues and 22% were in possession of antibodies. SQPV prevalence in sampled red squirrels was 2.5%. Viral loads were typically low in grey squirrels by comparison to red squirrels. There was a trend for a greater number of positive samples in spring and summer than in winter. Possible transmission routes were identified through the presence of viral DNA in faeces (red squirrels only), urine and ectoparasites (both species). Virus degradation analyses suggested that, after 30 days of exposure to six combinations of environments, there were more intact virus particles in scabs kept in warm (25 °C) and dry conditions than in cooler (5 and 15 °C) or wet conditions. We conclude that SQPV is present at low prevalence in invasive grey squirrel populations with a lower prevalence in native red squirrels. Virus transmission could occur through urine especially during warm dry summer conditions but, more notably, via ectoparasites, which are shared by both species.


Subject(s)
Chordopoxvirinae/genetics , Poxviridae Infections/veterinary , Sciuridae/virology , Animals , Antibodies, Viral/blood , Chordopoxvirinae/immunology , DNA, Viral/genetics , Disease Reservoirs/statistics & numerical data , Environment , Feces/virology , Introduced Species , Microbial Viability , Northern Ireland/epidemiology , Poxviridae Infections/blood , Poxviridae Infections/epidemiology , Poxviridae Infections/transmission , Prevalence , Seroepidemiologic Studies , Viral Load
16.
J Wildl Dis ; 49(4): 1070-3, 2013 Oct.
Article in English | MEDLINE | ID: mdl-24502745

ABSTRACT

Squirrelpox virus (SQPV) is a significant factor in red squirrel (Sciurus vulgaris) population declines but has previously been unconfirmed in the Republic of Ireland. In 2011 a juvenile red squirrel from Wicklow presented with facial, perivulval, and nail bed SQPV skin lesions confirmed by histopathology, PCR, and electron microscopy.


Subject(s)
Poxviridae Infections/veterinary , Poxviridae/isolation & purification , Sciuridae , Animals , Ireland/epidemiology , Poxviridae Infections/epidemiology , Poxviridae Infections/pathology
18.
Parasitology ; 139(5): 589-604, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22216952

ABSTRACT

Almost a decade has passed since the first report of RNA interference (RNAi) in a parasitic helminth. Whilst much progress has been made with RNAi informing gene function studies in disparate nematode and flatworm parasites, substantial and seemingly prohibitive difficulties have been encountered in some species, hindering progress. An appraisal of current practices, trends and ideals of RNAi experimental design in parasitic helminths is both timely and necessary for a number of reasons: firstly, the increasing availability of parasitic helminth genome/transcriptome resources means there is a growing need for gene function tools such as RNAi; secondly, fundamental differences and unique challenges exist for parasite species which do not apply to model organisms; thirdly, the inherent variation in experimental design, and reported difficulties with reproducibility undermine confidence. Ideally, RNAi studies of gene function should adopt standardised experimental design to aid reproducibility, interpretation and comparative analyses. Although the huge variations in parasite biology and experimental endpoints make RNAi experimental design standardization difficult or impractical, we must strive to validate RNAi experimentation in helminth parasites. To aid this process we identify multiple approaches to RNAi experimental validation and highlight those which we deem to be critical for gene function studies in helminth parasites.


Subject(s)
Helminths/genetics , RNA Interference , Research Design , Animals , Gene Transfer Techniques , RNA, Small Interfering/genetics
19.
PLoS Negl Trop Dis ; 5(6): e1176, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21666793

ABSTRACT

While RNA interference (RNAi) has been deployed to facilitate gene function studies in diverse helminths, parasitic nematodes appear variably susceptible. To test if this is due to inter-species differences in RNAi effector complements, we performed a primary sequence similarity survey for orthologs of 77 Caenorhabditis elegans RNAi pathway proteins in 13 nematode species for which genomic or transcriptomic datasets were available, with all outputs subjected to domain-structure verification. Our dataset spanned transcriptomes of Ancylostoma caninum and Oesophagostomum dentatum, and genomes of Trichinella spiralis, Ascaris suum, Brugia malayi, Haemonchus contortus, Meloidogyne hapla, Meloidogyne incognita and Pristionchus pacificus, as well as the Caenorhabditis species C. brenneri, C. briggsae, C. japonica and C. remanei, and revealed that: (i) Most of the C. elegans proteins responsible for uptake and spread of exogenously applied double stranded (ds)RNA are absent from parasitic species, including RNAi-competent plant-nematodes; (ii) The Argonautes (AGOs) responsible for gene expression regulation in C. elegans are broadly conserved, unlike those recruited during the induction of RNAi by exogenous dsRNA; (iii) Secondary Argonautes (SAGOs) are poorly conserved, and the nuclear AGO NRDE-3 was not identified in any parasite; (iv) All five Caenorhabditis spp. possess an expanded RNAi effector repertoire relative to the parasitic nematodes, consistent with the propensity for gene loss in nematode parasites; (v) In spite of the quantitative differences in RNAi effector complements across nematode species, all displayed qualitatively similar coverage of functional protein groups. In summary, we could not identify RNAi effector deficiencies that associate with reduced susceptibility in parasitic nematodes. Indeed, similarities in the RNAi effector complements of RNAi refractory and competent nematode parasites support the broad applicability of this research genetic tool in nematodes.


Subject(s)
Gene Expression Profiling , Helminth Proteins/biosynthesis , Helminth Proteins/genetics , Nematoda/genetics , RNA Interference , Animals , Conserved Sequence
20.
Int J Parasitol ; 40(11): 1303-10, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20398669

ABSTRACT

Micro-(mi)RNAs play a pivotal role in the developmental regulation of plants and animals. We reasoned that disruption of normal heterochronic activity in differentiating Meloidogyne incognita eggs may lead to irregular development, lethality and by extension, represent a novel target for parasite control. On silencing the nuclear RNase III enzyme drosha, a critical effector of miRNA maturation in animals, we found a significant inhibition of normal development and hatching in short interfering (si)RNA-soaked M. incognita eggs. Developing juveniles presented with highly irregular tissue patterning within the egg, and we found that unlike our previous gene silencing efforts focused on FMRFamide (Phe-Met-Arg-Phe-NH(2))-like peptides (FLPs), there was no observable phenotypic recovery following removal of the environmental siRNA. Aberrant phenotypes were exacerbated over time, and drosha knockdown proved embryonically lethal. Subsequently, we identified and silenced the drosha cofactor pasha, revealing a comparable inhibition of normal embryonic development within the eggs to that of drosha-silenced eggs, eventually leading to embryonic lethality. To further probe the link between normal embryonic development and the M. incognita RNA interference (RNAi) pathway, we attempted to examine the impact of silencing the cytosolic RNase III enzyme dicer. Unexpectedly, we found a substantial up-regulation of dicer transcript abundance, which did not impact on egg differentiation or hatching rates. Silencing of the individual transcripts in hatched J2s was significantly less successful and resulted in temporary phenotypic aberration of the J2s, which recovered within 24h to normal movement and posture on washing out the siRNA. Soaking the J2s in dicer siRNA resulted in a modest decrease in dicer transcript abundance which had no observable impact on phenotype or behaviour within 48h of initial exposure to siRNA. We propose that drosha, pasha and their ancillary factors may represent excellent targets for novel nematicides and/or in planta controls aimed at M. incognita, and potentially other parasitic nematodes, through disruption of miRNA-directed developmental pathways. In addition, we have identified a putative Mi-eri-1 transcript which encodes an RNAi-inhibiting siRNA exonuclease. We observe a marked up-regulation of Mi-eri-1 transcript abundance in response to exogenously introduced siRNA, and reason that this may impact on the interpretation of RNAi-based reverse genetic screens in plant parasitic nematodes.


Subject(s)
Cell Differentiation , Ovum/cytology , RNA Interference , RNA, Small Interfering/genetics , Tylenchoidea/embryology , Tylenchoidea/genetics , Animals , Female , Gene Knockdown Techniques , Helminth Proteins/genetics , Helminth Proteins/metabolism , Male , Ovum/enzymology , Ovum/growth & development , RNA, Small Interfering/metabolism , Ribonuclease III/genetics , Ribonuclease III/metabolism , Tylenchoidea/enzymology , Tylenchoidea/physiology
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